Cut-out for electric lamps



Feb? 9 'c.-sEvERlN ET AL CUT-OUT FOR' ELECTRIC LAMPS Filed July 25, 1931 Z' TUE-LE EARL E'EVERZZY, LE0 R.PETEE.5

IE-ICE'IB. Arrmzzr.

Patented Feb. 26, 1935 UNITED STATES cur-our Foa ELECTRIC LAMPS Carl Severin, Cleveland Heights, and Leo R.

v Peters, Cleveland, Ohio, assignors to General Electric Company, a corporation oi. New York Application July 23, 1931, Serial No. 552,724

3 Claims.

Our invention relates to incandescent lamps which are to be connected in series, and more particularly to such lamps which are provided with a cut-out to prevent the electrical circuit from being broken when one of the lamps in the series fails.

In certain service, several incandescent lamps are connected in series so as to use the customary electrical current available without the-use of a transformer or resistance. If a cut-out is not provided for each lamp, all of the lamps are extinguished upon the failure of any lamp in the series which must be located and replaced before the series will operate. This process requires considerable time and effort. The use of a lamp with a cut-out is to be greatly desired as the faulty lamp will be the only lamp in the series which will be extinguished.

An object of our invention is to provide a reliable cut-out in an incandescent lamp which can be conveniently and inexpensively manufactured. According to our invention, the cut-out comprises a body of material surrounding the lead wires and attached to an insulating body through which said leads pass. In the case of the ordinary Christmas tree lamp, the said insulating body is a bead of insulating material such as powdered silica which bridges both the leading-in wires. The material of the cut-out is preferably a mixture of a metal powder, a finely powdered insulating material and a binder made up into a paste. Iron powder of a fineness that will pass through 100 mesh screen and which has been reduced in hydrogen is preferred for the metal constituent. The binder may be sodium silicate. The insulating material may-be any inert material but preferably a non-hygroscopic material is used.

Powdered cryolite is a desirable material as anyv volatilized constituents thereof would not injure the lamp, but in fact might have "getter" action. Under ordinary operating conditions the sodium silicate and cryolite give the mixture insulating properties, but upon failure of the filament of a lamp in the series, the increase in voltage across the lamp terminals is such that the resistance of the cut-out is not suflicient to prevent the current from passing from one lead to the other.

In the accompanying drawing Flg.'1-is a side elevation of a decorative incandescent lamp embodying the cut-out of our invention; Fig. 2 is a side elevation of the bead portionof the mount on an enlarged scale and in an inverted position showing the cut-out; and Fig. 3 is a vertical sec- 5 tion through the center of that portion of the mount shown in Fig. 2.

The incandescent lamp shown in Fig. 1 comprises the bulb 10, the base 11 and the mount. The mount comprises the filament 12 having its extremities attached to leading-in wires 13 and 14 which in turn are held together by the head 15, preferably of glass. The leading-in wires connect to the shell and center contact of the base. Adhering to the bottom of the head 15 is 15 a mass 16 of material which acts as the cutout. The mass 16, as previously described, consists of a mixture of iron powder, cryolite powder and sodium silicate. The cut-out material in the particular form of our cut-out shown in Figs. 2 and 3 fills a depression 17 in the base of the head 15 allowing the said material greater contact area with the leading-in wires.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. In an electric lamp, the combination of a bulb, leading-in conductors extending within said bulb, an insulating body surrounding portions of said leading-in conductors and supported thereby and a paste cut-out member adjacent to said insulating body and surrounding a portion of each leading-in conductor.

2. In an electric lamp, the combination of a bulb, leading-in conductors extending within said bulb, an insulating bead surrounding portions of said leading-in conductors and supported thereby, and a paste cut-out member adjacent to said insulating bead and surrounding a portion of each leading-in conductor.

3. In an electric lamp, the combination or a bulb, leading-in conductors extending within said bulb, an insulating bead surrounding portions of said leading-in conductors, and a paste cut-out member partially supported by said bead and surrounding a portion of each leading-in conductor.

CARL srzvnam. LEO a. PETERS. 

